This invention relates to methods and apparatus for the repair of leaks at pipeline flanges and more particularly to methods and apparatus for the repair of such leaks in pipelines accomplished without interference with the operation of the pipeline.
The construction of pipelines involves many techniques, but always requires the joining of multiple pieces of pipe. The conventional methods of joining pipe together include such means as welding, threading, or the use of flanged ends which are bolted together. Where flanged bolted connections are used, it is not uncommon for leaks to occur in the junction between the two pieces of pipe whereby repairs are required for continued pipeline operation.
It is obvious that the preferred repair of a pipeline flange leak would be accomplished without the need to disassemble the flanged connection. Since pipelines are usually connected to operating systems at either end, it is frequently impractical to shut down the pipelines so as to facilitate the repair of the flanged connection.
Various techniques have been developed to attempt to stop such leaks at the flanged connections of pipelines without shutting down the pipeline. One such method uses a cable and a cable tensioning device to close the gap between the flanges and the area to be sealed and hold down wedge-shaped devices adjacent to the leaking area. A sealant is then injected into the gap between the wedges and the cable so that the cable seals and holds the sealant in place while it cures. The cable and tensioning device may then either remain in place to hold the sealant over the leak or the cable may be removed when sufficient friction forces are generated by the wedges to hold the sealant in place. This method seals only a portion of the periphery of the flanged section and is generally unsatisfactory where the seal is subjected to substantial internal pressure.
The disadvantages of the above method and other techniques and apparatus are overcome by the present invention in that the leak may be sealed while the pipeline remains in continuous operation and a permanent seal is provided around the entire periphery of the flange.